Abstract Grinding and flotation of sulfide-containing ores produce metastable, partially oxidized sulfur compounds known as thiosalts, which are notorious contributors to receiving water bodies’ toxicity by producing delayed acidity. Thus, the continuous optimization of thiosalts oxidation into sulfate is required before treated mine water is discharged into natural streams, as thiosalts oxidation slows down at low temperatures and in the absence of UV. With this aim, the present study evaluated the treatment of thiosalts at initial concentrations of 100 mg/L, 290 mg/L and 630 mg/L using three advanced oxidation processes (AOPs): (1) wet ferrates Fe(VI), 65 mg/L; (2) ozone microbubbles (O3-microbubbles), 75 g/h sparging rate; and (3) hydrogen peroxide (H2O2), 2:1 (H2O2:thiosalts) molar ratio, at 8 °C and 22 °C. All treatability tests were performed on synthetic effluents, while H2O2 efficiency was also assessed with a real effluent, a leachate of non-desulfurized tailings collected at a flotation plant. Results showed that O3-microbubbles gave better efficiency (99%) than wet Fe(VI) (82%) after 2 h of thiosulfate treatment. Similar trends were observed with synthetic and real effluents for treatment with H2O2. Efficient removal of thiosalts in the real effluent required several days of reaction at 8 °C (98%), whereas efficient removal at 22 °C (90%) was reached after 1 h of treatment. All three AOPs tested proved promising for thiosalts removal. The O3-microbubbles showed the best efficiency in terms of thiosalts removal and treatment time. Moreover, H2O2 allowed for better thiosulfate removal than wet Fe(VI), but proved inefficient at oxidizing other intermediate S species and required longer treatment time.

中文翻译：

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三种高级氧化工艺在矿井影响水中氧化硫盐的效率比较

摘要 含硫化物矿石的研磨和浮选会产生亚稳态、部分氧化的硫化合物，称为硫盐，这是众所周知的通过产生延迟酸度而导致水体中毒的原因。因此，在将处理过的矿井水排放到自然河流之前，需要不断优化硫盐氧化成硫酸盐，因为在低温和没有紫外线的情况下，硫盐氧化会减慢。为此，本研究使用三种高级氧化工艺 (AOP) 评估了初始浓度为 100 mg/L、290 mg/L 和 630 mg/L 的硫盐的处理：(1) 湿高铁酸盐 Fe(VI)，65毫克/升；(2)臭氧微泡(O3-microbubbles)，75g/h的鼓泡速度；(3) 过氧化氢 (H2O2)，摩尔比为 2:1（H2O2:硫盐），温度为 8°C 和 22°C。所有可处理性测试均针对合成流出物进行，同时还使用真实流出物（浮选厂收集的未脱硫尾矿的渗滤液）评估 H2O2 的效率。结果表明，在硫代硫酸盐处理 2 小时后，O3 微泡的效率 (99%) 比湿 Fe(VI) (82%) 更高。在用 H2O2 处理的合成和实际流出物中观察到类似的趋势。实际流出物中硫盐的有效去除需要在 8 °C (98%) 下反应数天，而在 22 °C (90%) 下处理 1 小时后即可达到有效去除。测试的所有三种 AOP 都证明有希望去除硫盐。O3-微泡在硫盐去除和处理时间方面表现出最佳效率。此外，H2O2 可以比湿 Fe(VI) 更好地去除硫代硫酸盐，